Remote control device for radio receivers



Nov. 24, 1936.

A. A. THOMAS REMOTE CONTROL DEVICE FOR RADIO RECEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet J INVENTO Nov. 24, 1936. A. A. THOMAS REMOTE CONTROL DEVICE FOR RADIO RECEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet 2 Nov. 24, 1936. A. A. THOMAS, 2,062,259

REMOTE CONTROL DEVICE FOR RADIO'REGEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet 3 Nov. 24, 1936. A. A. THOMAS 2,062,259

REMOTE CONTROL DEVICE FOR RADIO RECEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet 4 my; 6 I l 9 I I 25 m j i INVENTOR A. A. THOMAS Nov. 24, 1936.

REMOTE CONTROL DEVICE FOR RADIO RECEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet 6 INVENTOR zzw Nov. 24, 1936. A; A. THOMAS REMOTE CONTROL DEVICE FOR RADIO RECEIVERS Filed Feb. 26, 1930 7 Sheets-Sheet 7 Patented Nov. 24, 1936 PATENT OFFICE u REMOTE CONTROL DE"ICE FOB RADIO RECEIVERS Adolph A. Thomas, New York, N. Y., assignor to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application February 26,1930, Serial No. 431,377

4 Claims.

This invention relates to the art of tuning radio receivers from a distance, and its object-is to provide remote control apparatus of simple constructionand operation.

5 Briefly stated, my invention comprises a re mote control box having a set of keys or buttons which represent certain selected stations. When a key is pushed in, an electric motor in the radio cabinet actua'tes the tuning shaft, which operlo ates a switch arm arranged to move over a set of contacts. The circuit connections between the control box and the tuning mechanism in the radio cabinet are such that themovable switch arm automatically opens the motor-circuit when .a the selected station is in tune. The actuated key is thereupon released, but it'retums only part way to normal position and closes a signal circuit which lights a lamp adjacent the key. This lamp remains lighted until the key is fully restored to normal position, so that the operator can always identify the station tuned inlast. The cable that operatively connects the remote. control box with the radio cabinet contains only wires of low voltage, so that no danger of elect'ric shock or destructive arcing is possible. These electrical connections are so simple that only one wire for each key is required in the cable.

In addition to the automatic tuning keys, I preferably provide theremote control box'with a dialing key to bring in any station within range of the receiver. As long as the dialingkey is held down, the motor circuit is closed and the tuning shaft turns at sufficiently low speed to enable the operator to tellwhat kind of program is coming across as each broadcasting station is tuned in. When the operator gets what he wants, he simply lets go of the key and the station remains in tune. The loudspeaker circuit is always in operative condi- 0 tion when the dialing key is used, but the automatic tuning keys causesilent operation of the condenser shaft until the selected station is in tune. In other words, when the motor circuit is closed by one of the automatic "tun- 5 ing keys, the loudspeaker circuit is opened, and when the motor circuit is interrupted to stop the condenser shaft in tuning position, the loudspeaker circuit is automatically closed. This silent tuning feature is, however, not necessary 0 to the operation of the system'and may be Omitted.

Another feature of my remote control box comprises novel means for regulating the volume of reproduction. Heretofore it has been the common practice to control the loudspeaker volume by turning a knob one way or the other, but I use a pair of push' buttons, one for increasing the volume and the other for decreasing it. These two volume buttons control a rheostat arm in the receiver for regulating the loudspeaker 5 output in any practical way. I also provide the control box with a switch for turning the electric power on and off, irrespective of whether the main switch on the radio cabinet was left open or closed. A signal light on the control box informs the operator whether the power is on or 011. The receiver may be tuned by hand in the usual way, but I prefer to equip the same with a duplicate set of automatic tuning keys for preselected stations. This makes it possible to control the electric tuning mechanism either from the front panel of the cabinet or from the remote control box by no greater exertion than pushing a key or button, which even a. small child can operate.

At the present time, the universal method of tuning radio receivers is by adjusting condenser elements through an arc of 180 degrees. That is to say, the tuning shaft must be reversed after each half revolution, which means at each end of the indicator dial. When the tuning shaft is driven by an electric motor, it has heretofore been necessary to provide reversing connections for the shaft, either by electrically reversing the rotation of the motor shaft or interposing' a reversible drive between the two shafts. I do away with this complication by using a condenser structure in which the rotors always turn in the same direction. My novel condenser structure has the further advantage that the plates of each partcan be cast as a unit-thereby reducing the cost of manufacture and the labor of assembly. The indicator scale may be mounted directly on one of the condenser rotors.

The various novel features and practical advantages of my tuning system will be understood from a description of the accompanying drawings which illustrate a preferred embodiment of my invention. In thesedrawings,

Fig. 1 illustrates a radio cabinet equipped with my remot'control box;-

Fig. 2 represents an enlarged transverse section through the control box on line 2-2 of Fig. 1;

Fig. 3 is a section partly on line 3-3 of Fig. 2, except that the entire length of the box is'not shown forlack of space;

Fig. 4 shows how one of the automatic tuning keys is held locked against full return movement, the dotted lines indicating the key in normal positiong 56 Fig.5showsthesamekeyinfully position to close the associated switches;

Fig. 6 is a cross-section through one of the tuning condenser assemblies and associated parts in the radio cabinet;

Fig. 7 represents a sectional view on line I of Fig. 6;

8 is a diagrammatic outline of a condenser unit to indicate the interleaving of the plates;

Fig. 9 shows a face view of the switch mechanism controlled by the tuning shaft, this view being taken on line H of Fig. 6;

Fig. 10 is an exaggerated plan view sectioned approximately on the irregular line Iii-ll of Fig. 9 to show certain structural details in the mounting and arrangement of switch contacts;

Fig. 11 is a section on line ii-li of Fig. 10;

Fig. 12 shows an indicator ring having two oppositely arranged scales of 180 degrees each;

Fig. 13 is similar to Fig. 9, except that the station-selecting contacts are arranged in two semi-circular paths, this modification being used with the double indicator of Fig. 12; and

Figs. 14-15 together show diagrammatically the circuit connections between the remote control box and the radio cabinet.

Referring to Fig. 1, there is a radio receiver R of suitable construction and a remote control box K, which is operatively connected with the re ceiver through an electric cable II. In the present embodiment of the invention, I have assumed that eight selected stations can be automatically I tuned in from the control box K and so the latter is provided with eight tuning keys or push buttons l2. Opposite each key is a window it, which may bear suitable notations to identify the particular station represented by the key. The control box K is further provided with a dialing key it for tuning in any station within the operating limits of recei er R. Two keys or push buttons ii and it are used for controlling the loudspeaker vol time, one key increasing the volume and the other cutting it down. A rotary knob ll turns the electric power for the receiver on and off. when the power is on, a light shines through a brightly colored lens It. To bring in a station represented by one of the keys ii, the operator need only push in the proper key as far as it will go and hold it in that position until he hears the broadcast of the selected station through the loudspeaker. When .the key is released, the adjacent window I! automatically lights up as a visual identification of the station in tune. I may provide "for silent tuning by holding theloudspeaker cut out until the actuated key is released. It takes only a second or two for the electric motor in the radio cabinet to turn the tuning shaft to preselected po- 1 sition. If a person wants to get a station not represented by the keys I! or likes to explore the entire broadcasting range, he pushes in key It and listens for the broadcast of each station as it comes in tune. When key I4 is released,- the tuning shaft of the receiver instantaneously stops.

The front panel of radio receiver B may be provided with a set of automatic tuning keys I, which are a duplicate of keys it in the remote control box K and represent the same stations. Each key i9 has a window 20 which automatically lights up when the selected station is in tune. The buttons 2i and 22 are for the purpose of controlling the loudspeaker volume, the same as buttons-i and it of the remote control box. A

knob 23 on the receiver operates a switch for turning the electric power on and off. The

ably so connected that either switch is capable of turning the electric power for the receiver on and oil without regard to the condition of the other switch. The dialing key I of control box KisreplacedinreceiverRbyaknobIlfor manualtuningintheusualway,althoughadialingkeymaybeprovidedinthereceiverinlieu of the hand-tuning knob. A window II in the front panel of the receiver shows a suitable station indicator. I might explain at this point that when I refer to the parts It, and I! as keys or buttons, both in the description and claims, I use those terms in the broadest possible sense to include any practical form of hand-operable switch member, of which a key or push button is probably the most popular type.

The mechanism inside the remote control box KisshowninFigsz iwhichlshallnowdescribe in detail. The outer walls of the box, which may be of wood, bakelite or other suitable insulating material, comprise a base 2', sides 21, ends I. and a top plate or cover a. The underside of cover 29 carries a sheet lining 3. which is bent to provide flanges Ii for receiving screws 82 or other fastening members. The automatic tuning keys it pass through openings II in cover It and insulating bushings N of rubber or fiber may beusedtofurnishincreasedbearingsurfacefor the keys. A simple way to hold the bushings It in place is to provide them with an annular flange or shoulder 35 which fits in a recess 3! in top plate 29 and is engaged by the sheet lining II. This is clearly shown in Figs. 4 and 5. Each key I! comprises a stem 81 having a lower extension 89 and provided witha cap ll, which is preferably mounted for easy removal, as by engaging a screw ll mounted in the upper end of stem 31. The caps it may be molded of bakelite, celluloid, fiber, and the like, and each cap has marked thereon the call letters or other identifying marks of the by the keys. Thus, for example, the key cap for station WEAP may be blue, the cap for station WJZ may be red, and so on for the other stations.

Thestemsl'lofkeysiihaveeachapairof disks or rings ll and 42, between which is mounted an insulating'sleeve or bushing 48 of frustoconical shape. If the key stems 81 are of metal, the rings ll may be formed integral with the stems, but if the latter are molded of insulating material like hard rubber, "Bakelite", fiber. etc., the metal rings ll are attached separately. As will appear later, the rings II should be of good conducting metal which is not too soft. like certain kinds of ha d brass, bronae and other alloys and metals used for electrical conductors. The insulating sleeves or bushings 43 may be molded in place between the rings ll and 42. but it is probably easier to mold them and attach themtothekeystemsinanypracticalway. For example, the extension I! may be screwed into the lower end of stem 31 to lock the ring 42 and bushing llfirmlyinpositionagainstthecontact disk ll.

- The remote control box K has a transverse partition supported on brackets II carried by sheet metal linings l. which cover the sides 21. If the partition 44 fits snugly within the box, no separate fastening means is necessary, but screws 41 may b us d to connect the partition to brackets ll.

The linings 46 may be of stiff sheet metal like aluminum and secured to the base 26 by screws 46 or otherwise. The partition 44 is preferably a panel of, wood, bakelite, hard rubber, fiber, or other strong insulating composition. The key extensions 39 pass through holes 49 in partition 44 and guide pieces 56 are preferably attached to the underside of partition 44 in axial alignment with the bushings 64, whereby the keys are held steady in their reciprocable movements. An expanding coil spring 5| surrounds each key extension,39 between the ring or washer 42 and guide piece 56, as shown in Figs.,4 and 5. The normal tendency of spring 5| is'to hold the key projected,

this movement being limited by the ring 4| engaging the underside 64' of bushing 64. The inward movement of the keys against the action of spring 5| is stopped when the ring 42 strikes a collar 52 attached to the upper side of partition 44, as illustrated in Fig. 5. The same bolts 66 may be used for securing the parts 66 and 62 to the opposite sides of partition 44. The key extension 39 and guide pieces 66 are of good conducting metal and, electrically connected with the contact rings 4|, for a purpose to be later explained. A tongue or strip 56' attached to each guide piece provides an easy way to connect a conductor. I

The transverse partition or panel 44 carries a pair of brackets 54 for supporting and on which a plate 56 is pivoted. A contracting coil spring 51 normally holds the pivoted plate 56 in horizontal position against one or more stops 66 projecting from brackets 54. When the plate 66 is in normal horizontal position, as shown in-Figs. 4 and 5, the bevelled edge 56" is in contact with (or nearly. touches) the conical sleeve 43 at a point below the larger base 46' of the sleeve. In other words, the edge 56" oi. plate 66 is normally nearer to the axis of the key stem 91 than is the circumferential edge of ring 4|. Consequently, when the key is pushed in, the plate 56 is tilted to permit full inward movement of the key. As soon as the ring 4| of the actuated key passes the edge 56" of plate 56, the tensioned spring 51 pulls the plate back to normal position, thereby locking the key against full return movement. This will be clear by looking at Fig. 4. where the tilted position of plate 56 is indicated by the dotted outline 56a. Since the locking plate 56 is common to all keys l2, the actuation of a second key rocks the plate to position 56a and causes it to release the previously locked key. The locking plate 56 consists of good conducting metal, or at least that part of it which engages the rings 4| of the keys is a good conductor, because the additional function of plate 56 is to close a lamp circuit when it engages the metal ring 4| of an actuated key. I shall go into this more fully later on.

Referring to Figs. 2 and 3, a bracket 59 secured to one of the sheet linings 46 below the partition 44 carries an electromagnet 66. An armature bar 6| is pivoted at 62 between a pair of brackets or lugs 63 which project upwardly from the bottom plate 26 of the box. A contracting coil spring 64 normally holds the armature bar 6| against a stop 65. A vertical rod 66 is connected to the free end of armature 6| and projects through an opening in partition 44 into contact with the underside of the pivoted locking plate 56. It is clear from- ,Figs. 2 and 3 that when the electromagnet 66 is be explained later, the electromagnet," is automatically energized when any tuning key I9 of the radio receiver is actuated.

Still referring to Figs. 2 and item or. more brackets 61 are secured to the underside of partition 44 by screws or bolts 66, and these brackets carry an insulating-bar 69. Below each tuning key |2are three spring arms 16, 1| and 12, which are connected to bar 69 by three insulating strips 16. Bolts 14 hold the bar 69 and strips 19 connected to bracket 61, and at the same time clamp the spring arms 19, 1| and 12 rigidly in position. The spring arms 10 are separately insulated members, but the arms 1| are electrically connected to a common conductor and they can therefore be stamped as integral lateral extensionsof a metal strip 1|a. Similarly, the spring arms 12 may be integral lateral extensions of a conducting strip 12a. Any other practical means may be employed for supporting the sets of spring arms 16,

1| and 12 in operative relation to the tuning keys II. The ends oi the metal key extensions 39 are covered with an insulating pad or button 15, which may simply be a piece of hard rubber screwed to the inner end of each key. The spring arms-16, 1| and 12 constitute switch members .which normally remain open by their inherent set or tension. When a key I2 is pushed in as far as it will go, the switch armlll is moved into contact with arm 1| and the latter is forced into contact with arm 12. The circuits controlled by these switch arms will be fully described in connection with Figs. 14 and 15.

The windows IS in the top plate of control box K are enclosed by suitable frames 16, .which are shown rectangular but which may obviously be circular, elliptical, or of any other desired outline. The frames 16 can be stamped from sheet metal and are preferably removable individually from cover plate 29 for easy replacement of a window when necessary. The same remarks apply to frame 11 which carries the lens or jewel l6. Below each window i3 is a small electric lamp 16 and a similar lamp 19 is arranged below the jewel i6. The pilot lamps16 and 19 are mounted in wise. If desired, the lamp-supporting strip 6| may be secured to the underside of cover plate 29,

so as to'be removable therewith. To confine the light of each lamp 18 to the associated window 3, I provide shields 63 which may be formed integral with the sheet lining 36. When the cover 29 is removed, easy access is had to lamps 16 and 19, as well as to the other mechanism above partitlon 44. For access to the parts below partition 44, it is only necessary to take out the bottom screws 46 and remove the base 26. The mechanism in remote control box K is duplicated in the radio receiver, so that the foregoing description is also applicable to the key-controlled mechanism behind the escutcheon plate 64 on the front panel of the radio cabinet. The only difierence between the two mechanisms is the absence of the dialing key 4 in the radio receiver, although such a key may be used in place of the hand knob 24. The lens or jewel l6 in control box K is not duplicated in the escutcheon plate 64 of the radio cabinet, because the pilot light in the cabinet shines thrqugh the opening 26 when the power is on, as'I shall presently explain more fully. V

Figs. 6, 7, and ii show my novel condenser unit which permits rotation of the tuning shaft continuously in the, same direction by an electric motor. This condenser unit comprises a stator II and a rotor 88. The stator It consists of a base disk '1 provided with a set of semi-cylindrical plates It arranged in concentric spaced relation. A tubular bearing 89 projects centrally from the base member .1. The rotor 80 consists of a base disk provided with semi-cylindrical plates ll arranged inconcentric relation to overlap the stator plates 88 without touching them. The clearance between the two sets of plates is made as small as mechanical conditions permit. The condenser parts I! and 86 may each consist of a single casting of aluminum, duralumin, brass, or other suitable conducting material. To increase the rigidity of plates II and II, they may taper slightly toward their free ends as shown in Fig. 6. The number of plates on each condenser part may be varied in accordance with the size and maxi? mum capacity of the condenser, andas many condenser units may be employed as the receiver system requires. The shape of the condenser plates 82 and SI depends upon the rate of capacity variatlon obtained per unit angle of rotation. In Fig. 8 the stator plates I are square and the rotor plates 9i have a curved edge to give the requisite rate of capacity variation. At the present time most condensers are designed to give a straight line frequency eflect.

The condenser rotor 06 is secured to an insulatingplate 92 by screws 93, and this plate is fixed on a rotary shaft 94 by set-screw or otherwise. Roller bearings 96 support the tuning shaft 94 in the hub or sleeve 89 of stator 85, which is secured to the front panel 91 of the radio cabinet by screws 98 or otherwise. A suitable sheet lining 99 of metal or hard insulating material may be attached to the inner face of front panel 91. The outer end of shaft carries a sleeve I" to which the hand knob 24 is removably attached .by a setscrew IM or otherwise. In the particular construction shown in Fig. 6, the stator 85 is grounded to the metal framework in the cabinet, but it may be insulated like the rotor 86. A convenient way of connecting the rotor 86 incircuit is by supporting a spring-pressed brush or other contact member I02 in firmpressure engagement with the base disk 80 of the rotor. In Fig. 6 the contact brush I02 is mounted in afixed support Illl, which has a binding post I. For convenience I shall refer to shaft 94 as the tuning shaft, but that does not mean that the tuning elements must be mounted thereon. 0n the contrary, the tuning v elements may be mounted on separate shafts opsleeve I09 and screws III, or in any other practi-' cal way. The two shafts 94 and III are thus in effect a single shaft consisting of two insulated sections. The inner end of shaft. III is supported in panel Hi5, and a contact arm I I2 is fixed on the shaft at the proper angle. A set-screw III held' in the hub or sleeve Ill afiords an easy way to adjust the contact arm II2 to correct angularrelation to the rotor plates 9|. The free end of arm II2 carries a spring finger II! arranged to engage a set of contacts I I6 mounted in panel I".

Thesecontactsmaybescrewsadaptedtobeim.

sertedintothepanelfromtherearbyanordinary screwdriver, and the front ends of these screws are preferably rounded as indicated at H1 in Fig. 10. The contact finger II! terminates in a concave extension I II adapted to fit against the rounded ends I I1 of contacts I It. In this way the spring finger I Ills sure tomake a good electrical connection with each contact I it during the rotation of arm II2. If the hand-blob 24 is used for turning the tuning shaft 84 in either direction, the spring finger IIIisbentbackat IIO, so that the lateral extension III can easily slide over the rounded contact ends I I1 in either direction of rotation of arm I I2. To compensate for any wear in the rounded ends II1, the screw contacts II are individually adjustable in an axial direction.

In Fig. 9 the contacts Iii extend over half the circumference and are shown so close together as to represent practically all the stations that are licensed to broadcast. If it is desired to use the remote control box K for only a certain number of stations, it will be necessary to have only the same number of contacts Ill. For example, we may suppose that the eight tuning buttons l2 in control box K and the corresponding eight buttons I! on the front panel of the radio receiver are intended to tune in the stations identified in Fig. 9. In that case we need only eight contacts Iii arranged in correct angular relation, as can be easily determined by experiment. A spring finger I20 is mounted at one end on a lateral hit or block I 2I by screws I22, and the free end of this finger presses constantlyagainst the sleeve or bushing Ill of contact arm H2. The block I2I is secured to panel I" by screws I24. The contact finger I20 has a lateral extension I2l which passes through a slit I28 in the panel. The rear end of extension I is easily accessible for attaching an electric conductor, as shown in Figs. 10 and 11. Any other practical means may be used to connect the rotary contact arm H2 in circuit.

Referring .to Figs. 6 and 7, behind the window '26 in front panel 91 of the radio cabinet isa station indicator I21 in, the form of a flat ring of transparent or translucent material attached to the condenser rotor 06. outer semi-cylindrical plate ll of the rotor carries several right-angled lugs I22 for receiving screws I2! which pass through holes ISO in the indicator ring I21. As shown in Fig. 12. the ring I21 bears two complete tuning scales extending each a half circumference in opposite directions. For convenience each scale is marked with 100 For this purpose the divisions in accordance with the usual practice.

0 and DI are adjustable to the same position twice foreach revolution of shaft I. A pilot lamp I I2 is mounted behind the indicator ring I21 in line with window 25 to light e visible portion of the scale. The metal I22 of lamp I32 is carried by a right-angled metal bracket I" attached to the inner side of front panel 91 by a screw I", which may also be used as a binding post for a conductor. An insulated metal strip I36 engages the central contact of lamp I32. This arrangement makes it very easy to connect the lamp in circuit.

Figs. 14 and 15 illustrate diagrammatically the various circuit connections by which the radio receiver is tuned electricallyeither from the control box K or from the front panel of the cabinet. These two figures go together and are supposed to be a single figure separated along the imaginary line X-X. Since the mechanism associated with the automatic tuning keys I9 in the radio cabinet is the same as that within the control box K, I have indicated corresponding parts of the two mechanisms by like reference characters, except that for distinction I have used a prime mark with the reference characters of certain parts controlled by the keys I9. For example,

the switches 10', H and 12 associated with.

each key in the radio receiver corresponding to the switches 10, TI and 12 in the remote con- .trol box K; the individual signal lamps 18' in the radio receiver correspond to the signal lamps 18 in the remote control box; and so on for other corresponding parts in the control box and the radio cabinet. For distinction, the automatic tuning keys I2 and I9.are individually identified by the sufllx letters A--H, which may be regarded as representing the eight stations that have been selected for automatic tuning.- For the same reason, the eight contacts H6 in Fig. 15 are differentiated by the suillx letters A-H. The stations represented by the contacts INA-6H are identified in Figs. 9 and 13 by their call let-- ters. It goes without saying that the equal spacing of contacts II6A-I I6H in Fig. 15 is merely for convenience. An approximately accurate spacing of those contacts for the selected stations is indicated in Figs. 9 and 13.

Referring to Fig. 15, there is an electric motor I31 whose shaft I38 carriesv a slidable clutch ring I39 arranged to be operated by a bellcrank I40 pivoted at I on a suitable support I42 in the radio cabinet. The free end of lever I40 may be in the form of a yoke adapted to engage in an annular groove I42 of clutch ring I39 according to the usualpractice. A key or spline I43 on the armature shaft I38 locks the clutch ring I139 to the shaft for rotary movement therewith and at the same time permits axial movement of the clutch ring by bellcrank I40. A contracting coil spring I44 normally pulls the bellcrank I40 to the left against a flxed stop I45. The tuning shaft 94 carries a clutch member I46 adapted to interlock with the slidable clutch ring I39 when the latter is moved to operative position. The lower arm of bellcrank I40 is connected to a magnetic plunger I41 arranged to reciprocate in an electromagnetic coil I48. When this coil-is energized, the plunger I41 is pulled down and the bellcrank I40 is rocked clockwise to shift the clutch ring I39 into coupling engagement with clutch member 146. The tuning shaft 94 is thereby connected to the motor shaft I38 through a suitable speed-reducing device I38. When coil I48 is de-energized, the contracting coil spring I44 instantly pulls the clutch ring I35 away from clutch member I46, so that the tuning shaft 94 is disconnected from the motor. Another practical advantage of normally disconnecting the tuning shaft from the motor is that the radio receiver can be tuned by hand in the usual way without turning the motor shaft I38.

A plug I49 adapted to be inserted into a housesupplying the necessary electric power, as will be understood without further explanation. Two

branch conductors I52 and I53 lead from the' mains I50 and II and pass through the cable I0 to the remote control box K. A resistance I54 is included in conductor I53 to reduce the working voltage as required. In actual practice this reduced voltage need not exceed ten volts and less will probably be sufllcient. The service main I50 has an on-oif switch of suitable construction ranged to be engaged by switch arm I59. Suitable stop means in box K limit the rotary movements of knob I1 in such a way that when the knob'is turned one way, the arm I59 connects the diametrically opposite contacts I60, and when the knob is turned the other way as far as it will go, the arm I58 connects the two contacts I6I. The two left contacts I60 and I6I are connected in parallel to conductor I51, and the two right contacts I60 and I6I are connected to conductors I62 and I63 respectively.

The rotary hand-knob 23 at the front panel of the radio cabinet (see Fig. 1) is connected to a pivoted switch arm I64, which is shown diagrammatically in Fig. 15 at the left. Two pairs of contacts I65 and -l66 are arranged to be engaged by the rotary switch arm I64 when the latter is moved to one position or the other. That is to say, when the knob 23 is turned in one direction, the switch arm I64 connects the opposite contacts I65, and when the knob is turned the other way, the arm I64 connects the two contacts i615. Thetwo left contacts I 65ancl I66 are connected to conductors I63 and I62. respectively,

and the two right contacts I65 and I66 are connected in parallel to conductor 953. The relay coil I58 can be energized to close the main power switch I56 by turning either the knob I1 on the remote control box K or the knob 23 on the radio cabinet, and it makes no diiference in which position either knob was left. For instance, in Figs. 14-15 the switch arms I59 and I64 are in such position that the circuit of relay coil H8 is open. To energize this coil from the remote control box, the operator turns knob I1 until the switch arm I59 connects the two contacts I60, whereupon the circuit is closed through coil I58 as follows: starting from service main I5I, through resistance 54, conductor I53, across the switch contacts I66 which are connected by the conducting arm I64, through wire I62 in cable I0 across the contacts I60 which are now connected by the switch arm i59, through conductor I51 and coil I58 back to the return main I50. When a person wants to turn on the power from the radio cabinet (assuming that the arm I59 connects contacts I6I), he turnsthe knob 23 to connect the two contacts I65 by switch arm I64, whereupon the circuit of relay coil I58 is closed, as will be understood without tracing the circuit in detail.

Of course, a person operating either the knob of the remote control box or the knob 23 .of the radio cabinet cannot know in what position the switch arms, I59 and I64 were left, but it is only necessary to turn the knob one way or the other until the pilot lamps ll and Ill are lighted. These lamps, as will be seen in Fig. 14, are connected to conductors Ill and Ill, and they light when the switch Ill is closed. The electric power for the receiver may not only be turned on independently by theswitch arms Ill and ill, but it may also be turned oil! by actuating'either arm. For example,iiapersonturnsthe poweronby 10 means of knob ll on the radio cabinet, the power can be turned oil by simplymoving the knob ll on the remote control box until the lamp ll-is extinguished. Even though a person may not be using the remote control box. the lighting of lamp ll informs him that somebodyhas turned on the power in the radio cabinet. Likewise, a seeing alight shine thrc l thewindowll oithe radio cabinet is informed that somebody has turned the power on from the remote control box K. g

The station-selecting contacts lilA-lllH in Fig. 15 areconnectedtotheswitcharms Iloi the automatic tuning keys lu -"H in the remote control box by conductors lllA-illH respectiveiy, vThe switch contacts II are connected to conductors lllA-lllH, rapectively. These conductors are connected in parallel to a common conductor Ill, which is connected to conductor Ill. The swltcharms I! in theremote control box are connected to, conductors l'llA-lllH respectively; and these conductors areinturnconnected inparalleltoacornmon conductor ill, which is connected to a wire Ill in-cable ll. The switch arms I2 in the radio cabinet are similarly connected to a conductor Ill whichlnturnis connectedtothecablewire Ill. The switch arms Ii in the radio cabinet are connected in parallel to a common conductor Ill which corresponds to conductor Ill in the so remote controlboxandis likewiseconnectedto conductor ill. The switch arms W in the radio cabinet are connected to the wires ll'lAlllK in cable ll, the same as the switch arms 'Il in the remote control box. Theindividual station lamps llinthecontrolboxareconnectedst onesideto the metalkeystemsllandattheothersideto the common conductor "I through the parallel branches IRA-"UH. The individual I." I

intheradlorecelverare'connectedina similar soway. It willbeunderstoodthat theparailel branches illA-lllH andthe common conductor Ill represent tically the conducting stripliaintheremotecontrolmwhilethe otherstrip'llaisindigatedinl'lgdlbytheparallel branches illA-'-i'|lH and their The spring contact us, which su the hub Ill oi-the rotary arm 2 in the radio cabinet, is connected by a wire ill to conductor Ill eoArelaycoil l'llconnectedinseriesinwirel'll ture controls a movable switch arma normally engages a dud contact Ill connected toawirel'll. 'Ihiswireleadsiromthemotor less amount. A wire Ill leads from one side of the key-releasing coil ll in the remote control 5 boxtoc0nductorlllintheradiocabinet,and

thevolumeisincreased.

theothersideoithiscollisconnectedtothe common conductor ill in the control box. The wire Ill includes not only the key-releasing coil ll in the radio cabinet, but also a relay coil m which controls two iii-matures m and Ill. 1

ates) aswitcharm'lll whichmaybeintheio -iormoiaspringbladelikethe-switchmembers ll-ll. The normal set or tension of spring arm ill is such that it remains out of t with the associated contact Ill. A wire Ill connects the switch arm Ill with conductor ill to to which the pivoted key-locking plates ll and 'll'arealsoconnected-,asindicatedbywireslll and ill. The volume-control buttons ll and ll ontheremotecontrolbox oper'atespringanns Ill and Ill connected toconductor Ill. A wire Ill extendsfrom one sideoia solenoidcoil Ill intberadiocabinettoaswitchcontact lllin theremotecontrolbox.andtheothersiiieoiv thatcoilisconnectedbyawirellltoconduotor III. 'ihereiore,whentheloud"key ilispushed ll in. the switch Ill-ill is closed and coil Ill isenergised. .Awire Il-l leads from one sideoi a solenoid coil ll in the radio cabinet to a switch contact I in the remote control box. when the soit"-key ll is actuated, the switch so arm Ill engages contact Ill and the coil Ill is energized.

Reierringtol'ig. 15,thetwocoils illand ll! control a reciprocable magnetic plunger lll which comprises (or otherwise operates) a rack as barlllarrangedinmeshwithagearwheellll ct obtaining thisresult isto connect the llltothe'secondarycoilottheflrstaudio iormer,butthereareotherwaysoicon theloudspeaker volume. When the loud' ill is enemsed,the rheostst arm lll isrota tocutoutmoreoitheresistsncelllso :Emli

circuit of the soft coil Ill is closed.'tbe Ill is rotated the other way to cut in sistance and thereby decrease the volume.

solenoid plunger Ill preferably operates wi retardedmovementsothatthearmlllswings slow movement. plunger Ill an position.

In describin trol box K, w

d arm lll remain in actuated g the operation of the remote conemayassumethatapersonwislsss to tlmeinstation WEAF. Aiterturning oaths,

power switch by means of knob n, he pushes key I2A in as far as it will go. This operation' energizes the relay coil I84 through the following circuits: starting with service main I5I, through conductor I53 to point 2I I, conductor I88 to point 2I2, conductor I68A, through closed switch contacts "-12, conductors I18A and "I to point 2I3, connection 2I4 through coil 58, cable wire I83, through coil 38 and relay coil I84, conductors I13 and I52 to return main "I58.

The energizing of coil 88 in the remote control box performs no useful function at this time and may be disregarded, but the energizing of the corresponding coil 88 in the radio cabinet releases any previously actuated key for return to normal position. The energizing of relay coil I84 closes the switch contacts I85I81 so that the circuit through clutch coll I48 and electric motor I31 is closed as follows: from service main I5I, conductor I82, coil I48, conductor I8I, through the windings of motor I31, conductor I11, across the closed switches I13I15 and Ill-I81, and through conductors I13 and I52 to the return main I58. The energized coil I48 immediately couples the tuning shaft 84 to the motor shaft I38 through clutch members I38-I48, as previously explained, and the switch arm II2 rotates over the station-selecting contacts II8A--II8H. The energized relay coil I84 also opens the loudspeaker switch I 86-488 for silent tuning. This switch may, however, be omitted without affecting the operation of the tuning system.

When the arm I I2 engages contact I ISA (which represents station WEAF), the relay coil I14 is energized through these connections: from service main I5I, conductor I53 to point 2I I, conductor I88 to point 2I2, conductor I88A, through closed switch contacts 1I-18, conductor I61A, contact lIIiA, switch arm I I2, contact finger I28, conductor E13, coil I14, and through conductor i52 to the return main I58. The energizing of coil I14 opens the switch member I15 and breaks the clrcult of motor I31 and clutch coil I48. Consequently, the condenser shaft 84 stops instantly in tuning position for the selected station WEAF. The disconnection of shaft 84 from motor shaft I38 prevents the latter from communicating its momentum to the tuning shaft when the motor circuit is interrupted. This insures the stopping of shaft 84 in preselected tuning position and also permits hand tuning of the radio. receiver in the customary way. When the switch I86-I88 is used, the loudspeaker is not head until the actuated key is released, but the operator is sure of his station by holding the key down for a few seconds.

When the operator releases the depressed key I2A, the associated coil spring 5i (see Fig. 4)

throws the key up until the contact shoulder 4I strikes the metal locking plate 58. This closes the circuit through lamp 18 opposite key l 2A through conductor I88A (which is connected to service main I5I asabove explained), key extension 38, contact shoulder 4|, metal plate 58, conductors I83 and I82, and through wire I52 to the return main I58. The lamp 18 remains lighted until the key is returned to normal position, or until all the electric power is cut off. Thereturn of key It t to the position shown in Fig. 4 automatically ope; is the associated switch members 18, 1I and 12, so that the circuits through relay coils I14 and I84 are opened. Consequently, there is no waste of current in the tuning mechanism after. the selected nergized, the loudspeaker switch I85-I88 is automatically closed.

When any other tuning key I2B to I 2H is actuated to select a certain station, the operations above described for key I2A are repeated, except that the motor circuit is interrupted when the switch arm II2 engages the particular contact I I6 that is associated with the actuated key. For example, when'key I2D is pushed in, the circuit of motor I 31 is opened when arm II2 engages contact IISD, and so on for the other automatic tuning buttons. The same operations take place when the tuning keys I8AI8H on the radio cabinet are operated. When the double arrangement of contacts IISA-I [6H shown in Fig. 13 is substituted for the single arrangement of those contactsin Fig. 15, no change is necessary except connecting the corresponding contacts of each set a selected contact twice in each revolution, but

the motor circuit will be opened when the arm I I2 encounters the first one of the selected pair of contacts.

When the dialing key I4 on the remote control box K is pushed in to tune in on a suitable program without regard to the station it comes from, the motor circuit is closed as follows: service main I5I, conductor I82, clutch coil I48, electric motor I31, cablelwire I11, across the closed switch contacts I19l8l, and through conductors I92 and I 52 to the return main I58. The tuning shaft 84 is therefore rotated as long as key I4 is held in, and this operation is independent of switch arm H2 and contacts lit. When the operator gets a program that he likes, he simply lets go of key I4 and the tuning shaft stops instantly, because the motor circuit is interrupted.

Although I have shown and described certain specific constructions, I want it understood that my invention is not limited to the details set forth. It is to be expected that changes and modifications will occur to those skilled in the art in constructing my invention, without departing from the scope of the appended claims. It is not neces sary that all the various features of my invention shall be embodied in the same apparatus, for it is evident that some features may be used without v others.

I claim as my invention:

l. The combination ofia radio receiver having tuning mechanism, a set of keys for controlling said mechanism, a remote control box having a like set of keys for controlling said mechanism independently of said first set of keys, the'corresponding keys of each set representing a selected station, a locking device for each set of keys to prevent an actuated key from returning. to normal position, and means whereby the operation of a key in one setactuates the locking device of the in series with one of said contacts, and means whereby the closing'of said two series switches opens the motor circuit, the release of the actuated key automatically closing the loudspeaker circuit. 1

3. In 'a radio signal receiving system, a radio receiver having at least one.tuning element, a

motor for operating said tuning element, means at said motor including a plurality of conductors 1 station, conductors connecting said remote control station and said selectively operable circuit-controlling means, and mechanism including a plurality of interlocking keys at said remote control station for selectively extending said conductors terminating at said remote control station to complete a circuit for directively operating said circuit-controlling means, said keys being interacting so that the actuation of one key releases a 4. In a radio signal receiving system; a radio receiver having at least one tuning element, a motor for operating said tuning element, means at Ii said motor including a plurality oi conductors for selectively controlling the operation of said motor, a progressively movable switch for completing a circuit'tor said motor including one of said conductors. a remote control station, conduc- 10 torseonnecting said remote control station and saifprogresslvely movable switch, and mechanism including a plurality of interlocking keys at said remote control station for selectively extending said conductors terminating at said remote I control station to complete a circuit for directively operating said progressively movable switch, said keys being interacting so that the actuation of one key releases a previously actuated key.

ADOLPH A. THOMAS. $0 

